The present invention relates to a thermally conductive electrochemical sensor.
Electrochemical biosensors are well known. They have been used to determine the concentration of various analytes from biological samples, particularly from blood. Electrochemical biosensors are described in U.S. Pat. Nos. 5,413,690; 5,762,770 and 5,798,031; as well as in International Publication No. WO99/13101, each of which are hereby incorporated by reference.
An electrochemical biosensor typically includes a sensor strip and a sensor instrument. The sensor strip includes a space that holds the sample to be analyzed, may include reagents to be released into the sample, and includes an electrode set. The electrode set normally includes an insulating substrate, and electrodes that contact the sample, which have contact pads for electrically connecting the electrodes to the sensor instrument.
The temperature of the sample during analysis will effect the signal detected by the electrochemical biosensor. In order to compensate for variations in sample temperature, most electrochemical biosensors measure the ambient temperature, typically by using a temperature sensor in the sensor instrument, and contain electronics for electrochemical analysis. The temperature of the actual sample may vary from the ambient temperature, depending on the humidity and local air movements, by three degrees, or more. Furthermore, the ambient temperature is not necessarily stable, and therefore algorithms have been used to compensate for changes in ambient temperature (see, for example, U.S. Pat. No. 5,405,511, hereby incorporated by reference). In addition, if the instrument is held in the hand during use, the recorded ambient temperature may be effected by the temperature of the hand.
None of these devices actually measures the temperature of the sample, but rather simply use the ambient temperature measurements to indirectly determine the temperature of at the sample site, or the temperature close to the sample. It would be desirable to more accurately measure the temperature of the sample, thus avoiding the need for compensatory algorithms, and improving measurement accuracy.
In one aspect, the invention is a sensor strip, comprising (a) an electrode substrate, (b) an electrode set, on the electrode substrate, and (c) a heat conducting layer, on the electrode substrate opposite the electrode set.
In another aspect, the invention is a sensor strip, comprising (a) an electrode substrate, and (b) an electrode set, on the electrode substrate, where the sensor strip has a thermal conductivity of at least 10 W/m-K.
In yet another aspect, the invention is a sensor instrument for accepting a sensor strip comprising a gap, electrical contacts at a first side of said gap, and a temperature sensor, at a second side of the gap, opposite the electrical contacts.
In still another aspect, the invention is a method of making a sensor strip, comprising forming an electrode set on an electrode substrate; and attaching the electrode set to a heat conducing layer.
An advantage of the present invention is that it allows for accurate temperature measurement of the sensing region and sample.
As used herein, the phrase xe2x80x9celectrode setxe2x80x9d is a set of at least two electrodes, for example 2 to 60, or 3 to 20, electrodes. These electrodes may be, for example, a working electrode, a counter electrode, and a reference electrode.
Other features and advantages of the present invention will become apparent from the following detailed description. It should be understood, however, that the detailed description and the specific examples, while indicating embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.